Process for removal of sulfur and metals from petroleum materials



1969 a. P. MASOLOGITES ET PROCESS FOR REMOVAL OF SULFUR AND METALS FROMPETROLEUM MATERIALS Filed April 25. 1967 GEORGE F. MASOLOGITEJ PAUL J.wmrz 34/76 4 ATTDRNEY m S m m E m V m x E -2uo: N m A uh... J a m H 3 mQ m l 3am 23: .8300 .5300 Q m m 3:23am 1 now W l3 NM S1 boicotueu L R2w== o ..o-t=t= 5;. 22: R\ Nb v. R a Q C0 o oom 2 2 5 V a v 3.396 .2 2o. Q 3 g IQ 382.50 25 228mm 0 2 3. 13 5 2 2.38 v A A: 25? m 82 3 A N.3005:

30 228mm gotvoo f M United States Patent 3,472,759 PROCESS FOR REMOVALOF SULFUR AND METALS FROM PETROLEUM MATERIALS George P. Masologites,Broomall, and Harry E. Jacobs and Paul J. White, Media, Pa., assignorsto Atlantic Richfield Company, Philadelphia, Pa., a corporation ofPennsylvania Filed Apr. 25, 1967, Ser. No. 633,452 Int. Cl. 010g 37/02,13/02 US. Cl. 208-59 Claims ABSTRACT OF THE DISCLOSURE A process fortreating a petroleum material containing a residuum fraction in order toremove sulfur and metal compounds contained therein and to produce anaphtha fraction suitable for use as an ethylene charge stock and a lowsulfur content fuel oil comprising subjecting said petroleum material ata high temperature and high pressure to hydrocracking in the presence ofhydrogen and a catalyst, to produce a hydrocracked product, subjectingsaid hydrocracked product to hydrodesulfurization at a high temperatureand high pressure in the presence of hydrogen and a highly activecatalyst to produce a hydrodesulfurized product and then fractionatingsaid hydrodesulfurized product to obtain a naphtha product, a furnaceoil and a heavy fuel oil. The furnace oil is then recycled and subjectedto further treatment in order to increase the yield of the naphthaproduct.

BACKGROUND OF INVENTION This invention relates to the treatment ofpetroleum materials containing residuum fractions. Particularly, thisinvention relates to a process for the treatment of said petroleummaterials containing appreciable quantities of sulfur, nitrogen andmetal containing compounds. More particularly, this invention relates toa process for the treatment of said petroleum materials in order toproduce more valuable products, such as naphtha suitable for use as anethylene charge stock, and low sulfur content heavy fuel oil. Thenaphtha produced in the method of our invention has the desirablefeatures of an ethylene charge stock in that it will approximate avirgin naphtha from the standpoint of cyclic content and low iso tonormal ratio of paraffins. Further, the heavy fuel oil produced has asulfur content of less than 0.5 weight percent.

It has been known for some time that petroleum materials containingresiduum fractions contain significant quantities of metallicimpurities, e.g., vanadium, nickel, sodium, iron, copper and zinc. Theseimpurities may be in the form of insoluble compounds suspended in theoil or oil-soluble metallo-organic compounds. When petroleum materialscontaining residuum fractions are subjected to desulfurization,metallo-organic compounds present in such fractions tend to form a layerof ash on the surfaces of the catalyst, thus blocking or otherwiseadversely affecting the activity of the catalyst and often permanentlypoisoning it in terms of both activity and selectivity. This is quitedifferent from the ordinary inactivation of the catalyst by cokeformation which is alleviated by regeneration, e.g., burning ofi. of thecarbonaceous deposits formed during the reaction. While metallicimpurities present in such fractions in the form of suspended solidparticles may be removed by relatively simple physical means likefiltration, oil-soluble metallo-organic compounds present a moredifiicult problem of elimination. Accordingly, the art has necessarilyrelied upon various systems involving extensive replacement of thecatalyst. Replacement of the catalyst, however, necessitatesinterruption of the catalytic conversion operations or, as is morefrequently the case, the provision of duplicate reactors. In any event,costs associated with replacement of the catalyst have made it virtuallyimpractical to refine petroleum materials containing residuum fractionsof high metal content. Further, these metals, and in particularvanadium, are undesirable in residual petroleum fractions because of thecorrosion and pitting of metals resulting from combustion of suchresidual fuels.

With the increasing use of crude oils obtained from foreign sources suchas the Middle East and South America, the presence of the metallicimpurities in the crudes has become a considerable problem. The amountsof such metals in domestic sources of crude oil such as Mid-Continentand East Texas crudes, are so small as to present no problem in therefining of the crudes and in the use of the petroleum fractionsobtained from such crudes. For example, with two Texas crudes containingonly 0.1 part per million of vanadium and 2 and 4 ppm. of nickel, thecrudes can be processed satisfactorily in hydrogenation systems andtheir fractions employed in the usual Way. On the other hand with aKuwait crude containing 78 ppm. of vanadium and 28 ppm. of nickel in thelong residuum, the problem does exist; while with Venezuelan crudeswhich contain 200 to 1000 ppm. or more of vanadium and up to p.p.m. ofnickel in the long residuum, the problem is serious. Briefly stated, theoils with which this invention is concerned are those which containsuflicient amounts of heavy metals so as to cause catalyst contaminationproblems in desulfurization processes and/or corrosion problems in theuse as fuel. It is desirable to reduce the metals content to less than100 p.p.m. and preferably below 20 ppm.

It is also known in the petroleum refining art that the presence ofsulfur is objectionable in heavy fuel oils. High sulfur content in suchoils contributes significantly to air pollution problems.

SUMMARY OF INVENTION This invention is concerned with petroleummaterials containing residuum fractions such as total crude as Well astopped or reduced crude. These terms may be defined as follows:

Total crude is defined as a naturally occurring petroleum oil containingresiduum fractions which has not been processed in any manner, butpreferably separated from water and sediment and desalted.

Topped or reduced crude is defined as the residuum petroleum fractionresulting from removal of all or some of those straight run fractionssuch as gas, gasoline, kerosine, naphtha, furnace oil, gas oil, etc.,which are normally removed from the above defined total crude by theprocess of atmospheric and/ or vacuum topping or distillation. Ourinvention is, however, particularly suitable for the treatment ofreduced crudes.

It will be understood, however, to those skilled in the art that themethod of our invention will also be suitable for treating petroleumlike materials obtained from shale oil, tar sands and coal, saidpetroleum like materials having properties which are comparable topetroleum materials containing residuum fractions as hereinabovedefined.

In accordance with our invention, a petroleum material containingresiduum fractions, hereinafter referred to as charge stream, issubjected to a hydrocracking and hydrodesulfurization treatment. In thefirst stage the charge stream is subjected to hydrocracking in a firsthydrocracker. The total effluent from the hydrocracking stage is thensubjected to hydrodesulfurization. In these stages the material treatedis maintained largely in the liquid phase. The hydrodesulfurizedmaterial is subjected to fractionation in order to separate a naphthafraction, a furnace oil fraction and a heavy fuel oil fraction. Thefurnace oil fraction is then recycled and subjected substantially invapor phase to hydrocracking in a second hydrocracker in order toincrease the yield of the naphtha fraction.

The use of the first hydrocracker or the use of the desulfurizer alonecannot adequately treat a petroleum material containing a residuumfraction in order to economically and simultaneously remove sulfur andmetal compounds therein and to produce in high yield naphtha fractionsuitable for use as an ethylene charge stream. We have discovered,however, that in the combination of our process the first stage does aneffective job of demetallizing, and provides for adequate hydrocracking,while the second stage with its superior catalyst system, not onlyprovides for improved desulfurization but also hydrogenates the unstablecomponents of the efiiuent from the first stage. Improved yields ofnaphtha are obtained through use of the novel recycle step of ourinvention.

It is therefore an object of our invention to provide an improved methodfor the treatment of petroleum materials containing residuum fractions,i.e., fractions which cannot be practically distilled.

Another object of our invention is to provide an improved method for thetreatment of petroleum materials containing residuum fractions tomaximize the production of a naphtha fraction suitable for use as anethylene charge stock.

Still another object of our invention is to provide an improvedtreatment process for the removal of sulfur and metal compoundscontained in petroleum materials containing residuum fractions.

Yet another object of our invention is to provide an improved method forobtaining a naphtha fraction suitable for use as an ethylene chargestock and a heavy fuel oil having a low sulfur content whilesimultaneously limiting the production of furnace oil.

Other objects, advantages and features of our invention will be apparentto those skilled in the art without departing from the spirit and scopeof our invention, and it should be understood that the latter is notnecessarily limited to the accompanying discussion and drawing.

In a broad aspect, our invention relates to a process for removingsulfur and metallic compounds from a petroleum material containing aresiduum fraction in order to produce a naphtha fraction and a lowsulfur content fuel oil comprising cracking said petroleum materialwhile substantially in the liquid phase in the presence of hydrogen anda catalyst, desulfurizing the thus cracked oil while substantially inthe liquid phase with hydrogen in the presence of a catalyst comprisingessentially a minor amount of a member of the group consisting of oxidesand sulfides of metals of Group VI lefthand column of the PeriodicSystem and of iron group metals composited with a major amount of anactivated alumina prepared by drying and calcining a substance which ispredominantly composed of an aluminum hydroxide containing from 1.2 to2.6 mols of water of hydration to produce a desulfurized fraction, andthen fractionating said desulfurized fraction to obtain a naphthafraction, a furnace oil fraction and a heavy fuel oil fraction, andsubjecting said furnace oil fraction to hydrocracking whilesubstantially in the vapor phase in the presence of hydrogen and acatalyst in order to increase the yield of naphtha fraction.

DESCRIPTION OF DRAWING In order to more fully understand the method ofthis invention, reference is made to the accompanying drawing whichdiagrammatically represents a typical flow sheet embodying the process.Apparatus not considered necessary to' an understanding of the inventionhas been omitted.

Referring to the drawing, a charge stream enters line 11 and is pumpedby means of pump 12 through line 13 to heater 14 where it is heatedeither before or after mixing with hydrogen-rich gas. In the drawing thehydrogen-rich recycle gas passing through line 35 is combined with thefeed passing through line 13. The mixture of the charge and thehydrogen-rich gas passes through line 15 into the hydrocracker 16. Theeflluent from the hydrocracker passes by means of line 19, cooler 20 andline 21 into the hydrodesulfurizer 22. The desulfurized product leavesthe desulfurizer 22 by means of line 25, cooler 26 and line 27 andpasses into the high pressure separator 28. The desulfurized liquidbottoms material is withdrawn from the separator by means of line 29.

Gases from the high pressure separator 28 are withdrawn through line 31.A first portion of the gas flows from line 31 through line 32 toconventional gas recovery facilities. A second portion of the gas flowsthrough line 33 and is compressed by compressor 34. The gas then passesthrough line 35. This hydrogen-rich gas is preheated separately or inadmixture with the charge stream in heater 14. The admixture then flowsthrough line 15 as previously described.

Bottoms material in line 29 is heated by heater 56 before passingthrough line 57 to fractionating unit 58. Three fractions, viz., anaphtha fraction, a middle distillate or furnace oil fraction and aheavy fuel oil fraction are withdrawn from the fractionator throughlines 60, 61 and 59, respectively. A portion of the furnace oil fractionis withdrawn through line 68. The remaining portion passes through line61 to heater 62 and then through line 63 to second hydrocracker 64. Theeffiuent from this hydrocracking operation passes through line 65,cooler 66 and line 67 to separator 28.

Hydrogen-rich recycle gas is passed from line 35 through line 70 to line61. Hydrogen-rich makeup gas is added to line 70 by means of line 36.

PREFERRED EMBODIMENT In the first stage hydrocracker in the method ofour invention, the charge stream is subjected to liquid phasehydrocracking in the presence of a catalyst and a hydrogen-containinggas at elevated temperatures and pressures. Suitable hydrocrackingtemperatures fall in the range from about 700 F. to about 1000 F.,preferably in the range of from about 750 F. to about 900 F. Thispressure is maintained in the range of from about 500 p.s.i.g. to about5000 p.s.i.g., although a pressure in the range of from about 1500p.s.i.g. to about 3500 p.s.i.g. is preferred. Any conventional means forcontacting the charge stream with the hydrogen-containing gas andcatalyst can be used. For example, the process can be operated by usingvarious manipulative steps, e.g., upflow, downflow and horizontal flowof the liquid, concurrent and countercurrent flow of the gasiformmaterial relative to the flow of liquid and the use of solid contactmaterials in the form of fixed, moving and fluidized beds. Aparticularly suitable means for accomplishing the purposes of ourinvention resides in the use of an ebullated bed. In an ebullated bedreactor, the liquid and gasiform material is concurrently passedupwardly through a vessel containing particulate catalyst, the mass ofthe catalyst being maintained in random motion in the vessel by theupfiowing streams. The mass of catalyst in this state of random motionin the liquid medium is described as ebullated. The motion of thecatalyst makes the reactor free from pressure drop limitationsprevalently obtained in fixed beds due to carbon formation, and resultsin a narrow temperature gradient from the top to the bottom of thereactor. Ebullated bed reactors are now wellv known to those skilled inthe art. k

The total efiluent stream from the hydrocracker is then passed to ahydrodesulfurizer where it is contacted in the presence of a catalystwith hydrogen-containing gas at elevated temperatures and pressures. Thetemperature is maintained in the range from about 600 F. to about 850F., preferably from about 700 F. to about 825 F., and the pressure ismaintained in the range from about, 500 p.s.i.g. to about 5000 p.s.i.g.,preferably from about 1500 p.s.i.g. to about 3500 p.s.i.g. Anyconvenient means for effecting hydrodesulfurization can be used. A fixedbed reactor, however, is particularly suitable and is preferred.

In the second hydrocracker in the method of our invention, furnace oilis subjected to substantially vapor phase hydrocracking in the presenceof a catalyst and a hydrogen-containing gas at elevated temperatures andpressures. Suitable hydrocracking temperatures fall in the range of fromabout 700 F. to 1000 F., preferably in the range of from about 750 F. toabout 900 F. The pressure is maintained in the range of from about 500p.s.i.g. to about 5000 p.s.i.g., although a pressure in the range offrom about 1500 p.s.i.g. to about 3500 p.s.i.g. is preferred. Anyconventional means for contacting the furnace oil with thehydrogen-containing gas and catalyst can be used. A fixed bed reactor,however, is particularly suitable and is preferred. The hydrogensuppliedto the system need not be 100 percent pure hydrogen but maycontain such other constituents as nitrogen, methane, ethane, etc.Preferably, the hydrogen-rich gas stream should contain not less than 50volume percent hydrogen. The hydrogen-containing gas is recycled to line13 at a rate to provide at least 2500 s.c.f. of hydrogen per barrel ofcharge to the hydrooracker. Preferably, hydrogen is recycled to line 13at a rate to provide about 5000 s.c.f. to about 10,000 s.c.f. ofhydrogen per barrel of the charge to the hydrocracker. Hydrogen isrecycled to line 61 at the same rate (s.c.f. hydrogen per barrel ofmaterial passing through line 61) as indicated for recycle to line 13.Hydrogen makeup is added to the system in an amount equivalent to thatconsumed in reactions plus losses to the recovery system.

The liquid hourly space velocity in each of the reactors ismaintained inthe range from about 0.25 to about 5.0. Preferably, in the range fromabout 0.5 to 3.0.

: Applicable catalysts for the first and second hydrocrackers compriselow-acidity catalysts in the form of beads, pellets, powder, extrudatesor like particles. The size and shape of the catalyst employed dependson the particular conditions of the process, e.g., the density,viscosity and velocity of the liquid involved in the process.

In general, suitable catalyst include the metals .of Groups VI and VIIIof the Periodic Table of Elements, and their oxides or sulfides, eitheralone or in admixture with each other, deposited on amorphous metaloxide support wherein the metal oxide is selected from thegroupconsisting of silica, oxides of metals in Groups II-A, III-A andIV-B of the Periodic Table, and mixtures thereof. Examples of Group VImetals are tungsten and chromium, with the preferred Group VI metalbeing molybdenum in the form of a molybdate; examples of GroupVIII metalcomponents are cobalt and nickel; and. examples of the metal oxides inthe amorphous support are alumina, silica, zirconia, magnesia,.titania,ceria, thoria, etc. In particular, such catalysts are typified by nickelsulfide-tungsten sulfide, molybdenum sulfide or oxide, combinations ofmetal sulfides or oxides such as ferric oxide, molybdenum oxide orsulfide and cobalt oxide,- all of which are supported on the aboveamorphous metal oxide-supports. Other suitable catalysts includecatalysts having from about 1 to 10, preferably 2-4 weight percent of aGroup VIII metal oxide, preferably.;.cobaltoxide; and from about 5-30,preferably -15 weight percent of a Group VI metal oxide, preferablymolybdenum; supported on the amorphous metal oxide support, preferablyalumina.

The initial hydrocracking operation effectively accomplishes molecularweight reduction of the charge stream, partial-removal of sulfur, andeffective removal of metal containing compounds-thereby protecting thecatalyst bed in the subsequent hydrogenation stage.

The charge streams used in this process can vary widely in metalscontent and also in the type of the metals. The metals are containedprimarily in the asphaltene and resin components in the charge streamand under hydrocracking conditions in the first stage will react readilywith and be deposited on the catalyst. As the metals from the feedstream accumulate on the catalyst, they change its propertiessubstantially and will, together with the coke deposition that takesplace, reduce its activity. The principal metals to contend with arevanadium and nickel. However, the effect of the deposition of thesemetals is different since nickel is known to be an effectivehydrogenation metal, whereas vanadium is not. Since these metals arecontained in molecules that are high in molecular weight, theirdeposition is primarily on the surface of the catalyst particle.

Nevertheless, in accordance with another embodiment of our invention, wehave discovered that advantage can be made of this mode of deposition bymanufacturing extremely low cost catalyst in situ. This as accomplishedby employing a base which does not have strict purity requirements buthas a reasonable pore volume and surface area as the catalyst supportmaterial. Concentrations of less than 5 percent of molybdenum, cobalt,nickel, iron or mixtures thereof in such concentrations composited onsuch base materials provide sufficient hydrogenation activity tocatalyze the in situ manufacture of the catalyst by metal depositionfrom the charge stream when the charge stream has a metal contentgreater than about ppm.

A relatively inexpensive and preferred catalyst, containing l to 5percent by 'weight of an active metal such as nickel deposited on amodified fluid bed coke base is particularly eifective in the selectiveremoval of metals such as vanadium. Fluid coke not only contains adesirable particle size range but is very durable. However, in order tobe a suitable base or carrier for the active metal component, the fluidcoke must first be subjected to careful oxidation in a fluidized bed ata temperature level of about 700 F. until the material obtains a porevolume of at least 0.2 cc./gm. and a surface area of at least 50 squaremeters/gram. The active metal component is then added to the modifiedcoke material by impregnation in known manner. When this catalystbecomes contaminated with deposits of metallic impurities, catalystrejuvenation is readily effected by the method set forth in Connor etal. Patent No. 3,123,548 (1964) and Leum et al. Patent No. 3,041,270(1962) which methods are incorporated by reference herein.

Well-known hydrodesulfurization catalysts are not effective in themethod of our invention. A highly active catalyst must be employed. Wehave discovered that a particularly effective catalyst forhydrodesulfurization in the present method is a catalyst which comprisesa member of the group consisting of oxides and sulfides of metals suchas vanadium, chromium or molybdenum metals of the left-hand column ofGroup VI of the Periodic Table of Elements or iron, cobalt, nickel,platinum, etc. composited with a major amount of an activated aluminaprepared by drying and calcining a substance which is predominantlycomposed of an aluminum hydroxide containing from 1.2-2.6 moles of waterof hydration. The preparation of this catalyst is disclosed in Flinn etal. Patent No. 3,222,273 (1965), which patent is hereby incorporated byreference.

It should be understood that the flow sheet shown to illustrate theembodiment of the present invention is highly simplified for the purposeof clarity. Conventional means for heating and cooling, including butnot limited to the use of heat exchange with feed or products streams,can be employed in place of various heating and cooling units. It willalso be understood that, if desired, additional hydrogen can be added atvarious points within the system. Also, it may be preferable in someinstances to utilize multiple reactors in series or inparallel.

In order to more fully understand the method of our invention referenceis made to the following example.

EXAMPLE An integrated process similar to the complete processillustrated in the drawing is described in this example. As an aid tothe understanding of this example, reference will be made to the drawingWhenever applicable. A charge stream having the following composition isfed into conduit 11 at the rate of 10,000 bbls./day.

Charge stream: Lagomedio long resid. (47.2 vol.

percent of crude).

Gravity, API 17.4 Sulfur content, wt. percent 2.06 Vanadium content,p.p.m. 271 Nickel content, p.p.m. 24

At least 95 percent of this resid. material has a boiling point above675 F. The charge stream is combined with 10,000 s.c.f. of hydrogen/bbl.of feed. The combined stream is passed through heater 14 into thehydrocracker 16. Hydrocracking in unit 16 is carried out in the presenceof a cobalt molybdate catalyst containing 3 percent cobalt oxide and 12percent molybdenum oxide by weight on an alumina support at a pressureof approximately 2500 p.s.i.g. and at a temperature of approximately 850F.

The effluent from the hydrocracker 16 is cooled and then subjected tohydrodesulfurization in unit 22. Hydrodesulfurization in unit 22 iscarried out at a pressure of approximately 2500 p.s.i.g. and at atemperature of approximately 725 F.

The catalyst is nickel, cobalt and molybdenum (respectively, 0.5, 1.0and 8.0 percent by weight) deposited on calcined (1000 F. for hours)aluminum hydroxide containing 1.7 moles of water of hydration. Thecatalyst is prepared in the manner as set forth in Example I in PatentNo. 3,222,273 to Flinn et al. (1965).

The efiluent from the hydrodesulfurizer 22 is cooled in cooler 26 andthen flashed at 100 F. in separator 28. The liquid bottoms portionemerging from separator 28 is passed through line 29 and heater 56 inorder to raise the temperature for fractionation in unit 58. Heavy fueloil is removed from the fractionator 58 by means of line 59, and naphthais removed as an overhead stream through line 60. A furnace oil fractionis removed through line 61 at the rate of 3800 bbls./day. The furnaceoil fraction is combined with 10,000 s.c.f of hydrogen/bbl. of furnaceoil fraction. The combined stream is then recycled to hydrocracker 64.Hydrocracking in unit 64 is carried out in the presence of a cobaltmolybdate catalyst containing 3 percent cobalt oxide and 12 percentmolybdenum oxide by weight on an alumina support at a pressure ofapproximately 2500 p.s.i.g and at a temperature of approximately 850 F.The effluent from the hydrocracker 64 is then passed through a cooler 66into the separator 28.

The combined gas stream (line 32), naphtha stream (line 60), heavy oilstream (line 59) and the furnace oil stream (line 68) is removed at therates as follows:

C1-C3 .-1bS-/day (L -400 F. (naphtha fraction) bbls./day 5,500 Furnaceoil (0.1 wt. percent sulfur) (400 F.-

675 F. B.P. range) bbls./day 700 Heavy fuel oil (B.P. 675 F.+)(0.3%sulfur) bbls./day 4,600

The liquid hourly space velocity in hydrocracker 16 (ebullated bed)measured at the expanded bed condition is 1.0. The liquid hourly spacevelocity in hydrosulfurizer 22, and the second hydrocracker 64 is 1.0.

The hydrogen makeup gas passing through line 36 8 is added at the rateof 2900 s.c.f/bbl. of feed entering line 11. Gases, including hydrogensulfide, ammonia and hydrogen are removed from the system by means ofline 32.

The material leaving the hydrocracker 16 through line 19 has a nickelplus vanadium content of less than p.p.m.

Thus, a novel process is provided by the present invention for treatinghigh metal content petroleum materials containing residuum fractions toproduce a product from which high yields of naphtha suitable for use asan ethylene charge sotck and heavy fuel oil of low sulfur content can beobtained. Obviously, many modifications and variations of the presentinvention as hereinbefore set forth may be made without departing fromthe spirit and scope thereof.

What is claimed is:

1. A process for removing sulfur and metallic compounds from a petroleummaterial containing a residuum fraction and having therein metalliccontaminants in excess of 100 p.p.m., comprising the steps of:

(l) cracking said petroleum material while substantially in the liquidphase in the presence of hydrogen and a catalyst in a first hydrocrackerat a temperature in the range from about 700 F. to about 1000 F., at apressure in the range from about 500 p.s.i.g. to about 5000 p.s.i.g.,

(2) reacting the thus cracked oil at a temperature in the range of fromabout 600 F. to about 850 F. and at a pressure in the range from about500 p.s.i.g. to about 5000 p.s.i.g. while substantially in the liquidphase with hydrogen in the presence of a catalyst comprising essentiallya minor amount of a member of the group consisting of oxides andsulfides of metals of Group VI left-hand column of the Periodic Systemand of iron group metals composited with a major amount of an activatedalumina prepared by drying and calcining a substance which ispredominantly composed of an aluminum hydroxide containing from 1.2 to2.6 moles of water of hydration, in order to produce a hydrodesulfurizedproduct,

(3) fractionating said desulfurized product to obtain a naphthafraction, a furnace oil fraction and a heavy fuel oil fraction, and

(4) subjecting at least a portion of said furnace oil fraction tosubstantially vapor phase hydrocracking in a second catalytichydrocracker at a temperature between about 700 and 1000 F. and at apressure in the range of about 500 p.s.i.g. to about 5000 p.s.i.g. tomaximize production of a naphtha fraction.

2. The process according to claim 1 wherein the cracking of saidpetroleum material in the first hydrocracker is performed at atemperature in the range from about 750 F. to about 900 F. and at apressure in the range of from about 1500 p.s.i.g. to about 3500 p.s.i.g.

3. The process according to claim 2 wherein the metals content of thepetroleum material is reduced to less than 100 p.p.m. by cracking in thefirst hydrocracker.

4. The process according to claim 2 wherein the hydrocracking in saidsecond hydrocracker is performed at a temperature in the range fromabout 750 F. to about 900 F. and at a pressure in the range of fromabout 1500 p.s.i.g. to about 3500 p.s.i.g.

5. The process according to claim 2 wherein the reacting of the thuscracked oil is performed at a temperature in the range of from about 700F. to about 825 F. and at a pressure in the range of from about 1500p.s.i.g. to about 3500 p.s.i.g.

6. The process according to claim 2 wherein said cracking in said firsthydrocracker and said second hydrocracker takes place in the presence ofa catalyst comprising 3 weight percent cobalt oxide and 12 weightpercent molybdenum oxide on alumina support.

7. The process according to claim 1 wherein said first hydrocracker isan ebullated bed hydrocracker.

3,472,759 9 l0 8. The process according to claim 1 wherein saidReferences Cited cracking takes place in the presence of a catalyst com-UNITED STATES PATENTS prising less than about 5 weight percent of anactive metal 2,917,456 12/1959 Ashley 208--216 of the group consistingof molybdenum, cobalt, nlckel, 2 987 467 6/1961 Keith et a1 iron, ormixtures thereof supported on a carrier material. 5 3180817 4/1965claussen et 208*59 9. The process according to claim 8 wherein saidcarrier material is fluid bed coke having a surface area of at DELBERTE, GANTZ, Primary Examiner least 50 square meters/gram and a pore volumeof at A RIMENS Assistant Examiner least 0.2 cc./ gm.

10. The process according to claim 9 wherein the 10 US CLXR' activemetal is nickel. 208-97, 111, 209, 216, 251

